Transformer



June 27, 1933. v L 'f 1,916,007

TRANSFORMER Filed July 28, 1932 lnvencov; MonTviHe B.Ma| |ett,

His Attorney.

Patented June 27, 1933 HONTVILLE B.

MALLETT, OF PITTSFIELD, ELECTRIC COMPANY, A CORPORATION OF NEW YORK MASSACHUSETTS, ASSIGNOB '10 GENERAL TRANSFORMER Application filed July 28, 1932. Serial No. 825,245.

My invention relates to transformers and more particularly to transformers having three or more windings. Transformers are often operated under conditions where the voltage of the primary circuit is variable but.

Where it is desirable that the voltage of the secondary circuit be maintained at a constant value. Under such conditions, it is customary to provide one of the transformer windings with taps to permit the number of effective turns in the tapped winding to be varied. Thus, the voltage ratio of the transformer may be varied to compensate for any variation of the primary voltage and the secondary voltage may be maintained at a constant value. r r

A variation in the voltage at the terminals of the primary winding will cause a corresponding variation in the induction in the transformer core and this in turn will cause a variation in the secondary voltage. If the primary winding is provided with taps, any variation of primary voltage may be compensated by chan 'ng the number of effective primary win ing turns to restore the secondary voltage to its desired constant value by restoring the induction in the core also to its previous corresponding value. If

the secondary winding is provided with the taps, the number of effective turns in the seconda winding may be changed to compensate or a change in the induction in the core due to a variation in the primary voltage to restore the secondary voltage to its desired constant value.

Some transformers have three or more windings of which one is a primary winding and the others are secondary windings. Any variation in the primary voltageof such a transformer may e compensated by changing the number of effective turns in the primary winding by taps provided in that winding to keep the induction in the transformer core and, therefore, the voltageof each secondary winding constant. However, there ma be reasons such as high voltage and insulatlon difiiculties in the primary winding which make taps in the primary winding undesirable. It is also undesirable to provide taps in each of the secondary windings as such ings of a three windin a multiplicity of taps would be complicated and expensive. The general object of the invention is to provide a transformer having more than one secondary winding with improved means including taps in a single sec ondar windin for regulating or ad usting the v0 tage of a l the secondary windings.

The invention will be explained more fully in the followin nection with t e accompanyin drawin which is a diagrammatic view 0 the win transformer provided with voltage regu ating means in accordance with the invention.

The drawing shows-a transformer rimaryv winding 10 and two secondary win ings 11 and 12, One'of the secondary windings 12 1s provided with taps 13 and a ta switch 14 for varying or adjustin the num er of effective turns in this secon ary winding. Thus,

the voltage of this secondary winding may be mamtalned at a constant value if the voltage of the primary windin 10 should vary. Changing the number 0 effective turns in the secondary winding 12 cannot alone, however, maintain a constant voltage in the other secondary winding 11.

description taken in con- The voltage of thesecondary windin 11 is regulated by a small auxiliary trans ormer havmg two windin 15 and 16. The winding 16 of the auxi iarg transformer is cont e secondarywinding nected in series with 11 and the other winding 15 of the auxiliary transformer is connected across the tap switch 14.- In the arran ement shown in the drawing, one end of t e winding 15 is connected through a conductor 17 to the movable contact of the switch 14 and the other end is connected through the conductor 18 to one ofthe ta 5 13'but other arrangements "may ebvious y be used.

When the switch 14 connects the conductor 17 to the same tap 13 to which the conductor 18 is connected, the auxiliary transformer winding 15 is short-circuited and, therefore, induces -no volta in the winding 16 and does not change t e voltage between the fer-V minals of the secondary windin 11. When the switch ll connects the conductor 17 to some other tap13 than the one to which-the conductor 18 is connected, then the section of the winding 12 which is between these two ta 3 is connected across the windi 15 so t at a voltage is induced in the win in 16.

ssume that the primary voltage between the terminalsof the winding 10 is inducing the desired secondary voltages in the windings 11 and 12. An increase or decrease in the primary voltage will cause a corresponding increase or decreasein the induct1on in the core and in the secondary voltages in the windings 11 and 12. The volta e of the winding 12 may be corrected or a justed to its desired value by increasing or decreasing its effective number of turns b means of the tap switch 14. As the mova e contact of the switch 1&- ischengcd, there is a corresponding chenge in the voltage between this contact and the conductor 18 and, therefore, in the voltage induced in the winding 16. The voltage ratio of the windings l5 and it is madeto reduce 2i voltage in the windi 16 of just t e proper value to compensate for the clone in the induction in the core end thus to correct or adjust the voitage between the terminals of the secondary winding iii to its desired value If? the conductor 18 is connected to an intermediate tap '13 ee drown in the drawing, the voiteof the winding it will be added to the voltage of the "winding ll when the movable contact oft theewitch i4: is at one side of this ininrmedinte tep end will 0 pose the volt-ego of? the winding 11 when t e switch contact is nt the other side of this intermcdiete contract. The invention prow'des n sirn'plle eiiticient means tor edjneting the voltages oi two or more secondary windinge where in the primery winding ere nndesirnble end without the necessity oi eny tnpe in more then one of the secondnry windii The invention hes been enpinined Ry describing end ilinetreting e perti c 'epli cntion therein to e trensioimer secondery windings font it that -lL be inside withont ing from the spirit of? the invention end the eco oi? the eppended cin'ime. v

fillet claim on new desire to secnre by lintters "Pet ant oiE United States is:

i. A trenei onner incinding st ii windings ench winding being new 7 tween e pnir eii one being provided with taps, the terminals i s aid tapped winding being arranged for connection to an external 1 circuit, means for changin the tap connections to va the efi'ective v0 ta between said termina of the tagped winding, and means controlled by sai tap connection changing means for varying the voltage in the circuit of another of the transformer windings.

2. A transformer including a prima winding and a plurality of sccondar win ings, each winding being connected tween a pair of terminals, one of said secondary windings be provided with taps, the terminals of sai tapped winding being arranged for connection to an external load circuit, means for chan g the tap connections to vs. the efl'ective volta between said termina s of the ta ped secon ary winding, and means contro led by said tap con= nection c means for varyin the volta' in the circuit of another 0 said secon ar'ywindinge.

3a, A transformer including a primar winding and adplurality ofseconda win ings, each win connected tween e pair of termin a one o'f said secondary windings bein provided with taps, the terminals of saifi tapped winding being arranged for connection to an external load circuit, means for chan mg the tap connections to v the edective voltage between said terminals of the tapped secondary winding, and an eum' liieryi transformer with one winding connected across said tap connection c means and a second winding eonvw in series with another of said secondcry w: r19:v i p d. A tionner including a prime winding and egnlnrelity oi secondargewin inge, each win ing being connected tween e pair of terininnle, one of said secondary windings hein provided with tape, the teroii eai tapped winding being ar- 1 U for connection to an external load nit, e top switch conn to said taps tier varying the effective voltage. between eeicl terminals of the tapped seconda winding, we en enniiiery transformer with one windin connected no eeid tap switch end or eecon winding connected in series with another oi? eeid secondery windings.

Kn whereoi K have hereunto set- 

